Conventionally, as a semiconductor manufacturing apparatus of this type, use has been made of a plasma processing apparatus as described in Japanese Unexamined Patent Application Publication (JP-A) No. 2002-299330 (hereinafter referred to as Document 1). As described in Document 1, this plasma processing apparatus comprises a radial line slot antenna (hereinafter referred to as an antenna) adapted to radiate a microwave into a process chamber, a phase delay plate adapted to compress the wavelength of the microwave radiated from the antenna, and a cover plate disposed at an interval from the phase delay plate. The plasma processing apparatus further comprises a shower plate made of a low-loss dielectric, having a number of gas ejection holes, and disposed immediately below the cover plate. Further, a conductor construction having a number of nozzles is disposed under the shower plate at an interval therefrom.
A gas for plasma generation is supplied to the inside of the shower plate. When the microwave is applied from the antenna in this state, a high-density plasma is generated in a space between the shower plate and the conductor construction. This plasma is introduced through the conductor construction into a process space where a semiconductor wafer is processed. With such a configuration, a process gas ejected from the nozzles of the conductor construction is excited by the high-density plasma formed under the shower plate.
In this case, the shower plate is formed with a plasma gas supply passage communicating with a plasma gas supply port provided in an outer wall of the process chamber. From the plasma gas supply port, the plasma excitation gas such as Ar or Kr is fed to the supply passage in the shower plate. Further, the excitation gas is introduced into the process chamber through the supply passage and the gas ejection holes of the shower plate.
In the foregoing plasma processing apparatus having the radial line slot antenna, the uniform high-density plasma is formed in the space immediately below the shower plate. The high-density plasma thus formed has a low electron temperature. Therefore, no damage occurs to the processing substrate and no metal contamination occurs due to sputtering of the wall of the process container either.
On the other hand, a number of the gas ejection holes of the same size are equally and uniformly disposed in the shower plate. In other words, the distribution and size of the gas ejection holes arranged in the shower plate are uniform over the entire surface of the shower plate.
According to experiments by the present inventors, it has been found that, using a shower plate with gas ejection holes of the same size uniformly distributed over the entire surface, when the film formation process such as CVD (Chemical Vapor Deposition) is carried out, the thickness of a film formed on a substrate becomes unequal, while, when the etching process such as (RIE) (Reactive Ion Etching) is carried out, the etching rate becomes unequal. Further, it has also been found that there arise problems of unstabilization of the process, degradation in yield, and degradation in throughput due to process gas deposition on the shower plate.
An object of this invention is to provide a technique for clearing up the cause of various faults inherent to the foregoing plasma processing apparatus and enabling to reduce those faults.
A specific object of this invention is to provide a plasma processing apparatus or a semiconductor manufacturing apparatus that can realize uniform film formation or uniform etching rate.
A further specific object of this invention is to provide a shower plate that serves to realize uniform film formation or uniform etching rate.
Another object of this invention is to provide a method of manufacturing a product by the use of the foregoing shower plate.